Not applicable.
Not applicable.
This invention relates generally to medical devices, and more particularly to a catheter which can be formed, inside the human body, into a vast number of different shapes.
Selective catheterization of cerebral and visceral branch arteries is often difficult and at times impossible in some patientsxe2x80x94particularly older patients with very tortuous and ectatic vasculature. Successful catheterization sometimes requires multiple catheter exchanges for various shaped catheters. It is not uncommon to easily catheterize three of four vessels for a four vessel head study, only to find that the fourth vessel (generally the left or right carotid) requires an entirely different catheter shape and tip orientation. It would be desirable if one could easily and simply reshape the catheter and reorient the tip to direct it into the vessel orifice, instead of depending on several complex catheters that require reformation, fancy torque and advancing maneuvers, body english and, above all, luck.
Tip reorientation, the goal of most prior devices which have addressed the problem, is only half of what is needed to make a truly workable universal catheter. Numerous catheter curve configurations have been conceived not only to reorient the tip properly for selection of branch vessels, but also to provide anchorage of the catheter against the aortic wall. A wide looped long tipped sidewinder III configuration with an exaggerated retrocurve is one such example of a highly specialized complex catheter.
This anchorage or wedge effect against the aortic wall lessens the recoil caused by the xe2x80x9cjet effectxe2x80x9d during high pressure contrast injection which might otherwise cause the catheter to flip out of the selected branch vessel (particularly in short branch vessels or at levels of a dilated aorta).
These complex configurations, therefore, evolved not only to orient the tip properly, but also to wedge the catheter securely in the branch vessel. Other devices which simply modify the distal catheter curve may aid in tip orientation for vessel selection, but fail to provide the anchorage which is necessary to prevent catheter dislodgement.
In addition, prior designs could be improved in that the radii which the prior devices are able to make (to enter a vessel at a sharp angle, for example) have heretofore been severely limited.
Moreover, the size of prior designs has made them less desirable for many applications.
In certain applications (for example, complex interventional procedures such as angioplasties or intracerebral procedures), current catheters could be improved with respect to their ability to facilitate crossing of tight stenoses or with respect to their trackability out into peripheral branches.
In this respect, the current catheters could be improved in the areas of displacing forces from the application site at the point of catheter introduction (most often in the inguinal area) to points close to the actual catheter tip. This would increase the control that a user, such as an angiographer, has on the catheter, creating a more precise local longitudinal vector force for crossing tight stenoses, and also increase torque force for guiding the catheter tip toward the orifice of a selected vessel.
It would also be desirable to have a catheter construction which provided controllable variability in the distal catheter stiffness. Such a catheter could be stiffened for support close to a first order selected branch through which a more flexible catheter could be tracked peripherally. Conversely, such a catheter could be made less stiff over variable distances to allow better tracking of a more flexible distal end over a guidewire.
Among the various objects and features of the present invention may be noted the provision of a catheter which simplifies the catheterization procedure.
A second object is the provision of such a catheter which significantly reduces the number of catheterizations required for any particular medical procedure.
A third object is the provision of such a catheter which can be easily and simply reshaped into a variety of different shapes as desired by the user.
A fourth object is the provision of such a catheter which can mimic almost any catheter configuration, and can thereafter be reformed in the body to other desired shapes.
A fifth object is the provision of such a catheter which obviates the need for multiple catheter exchanges, thereby reducing the time involved in a medical procedure and also reducing the possibility of complications.
A sixth object is the provision of such a catheter which provides adequate anchorage of the catheter against the aortic wall to reduce the xe2x80x9cjet effect.xe2x80x9d
A seventh object is the provision of such a catheter which is capable of achieving an improved curve radius at its distal end.
An eighth object is the provision of such a catheter which is significantly reduced in size compared to the prior devices.
A ninth object is the provision of such a catheter which will displace longitudinal vector force from the site of application in the groin of the patient to a point near the tip of the catheter, thereby facilitating the crossing of tight stenoses during angioplasty procedures.
A tenth object is the provision of such a catheter which will displace torque force from the site of application in the groin of the patient to a point near the tip to facilitate more precise torque of the catheter tip, improving the ability to enter selected vessels.
An eleventh object is the provision of such a catheter which will provide variable stiffness at the distal end that will facilitate catheter advancement peripherally when it serves as a stiffened support near a first order take off vessel and will likewise facilitate tracking over a guidewire when made more flexible over a variable distance, distally.
Other objects will be in part apparent and in part pointed out hereinafter.
Briefly, a combination catheter of the present invention includes a catheter tube having a wall and an internal lumen extending substantially through the length of the catheter tube. The catheter tube has an outside diameter sufficiently small so that the catheter tube may be inserted into the human body and has a proximal end and a distal end. The catheter tube also has a remotely controlled deflectable distal tip and a substantially uniform transverse cross section throughout a substantial part of its length. The catheter tube wall adjacent the distal end of the catheter tube has a predetermined reference position therein on one side of the longitudinal axis of the catheter tube. An inner surgical element is disposed in the lumen of the catheter tube, the inner surgical element being rotationally and axially movable in the lumen of the catheter tube and being sufficiently pliable to bend upon bending of the catheter tube. Manually operable structure is provided for fixing the inner surgical element in desired rotational positions with respect to the catheter tube.
In a second aspect of the present invention, a transformable catheter includes a sheath having a diameter sufficiently small so that the sheath may be inserted into blood vessels of the human body. The sheath has a length which is a substantial fraction of the entire length of the transformable catheter, a bore therethrough running substantially from the proximal end of the sheath to the distal end of the sheath, and a remotely controlled deflectable distal tip. A preformed inner catheter sized to fit in the sheath bore is axially and rotationally movable with respect to the sheath in the bore, whereby by suitable manipulation of the inner catheter with respect to the sheath and of the distal end of the sheath the shape of the exposed portion of the distal end of the inner catheter may be reformed and transformed to any of a variety of shapes as desired by the user. Manually operable structure is provided for fixing the catheter in any desired rotational and/or longitudinal position with respect to the sheath.
In another aspect of the present invention, manipulating the shape of a combination catheter in a human body is accomplished by inserting a catheter tube having an internal lumen into a human body, wherein the catheter tube comprises a proximal end and a distal end, and a first curve controllably formed in the distal end with a first radius of curvature. An inner medical element is disposed at least partially in the lumen of the catheter tube to thereby form a combination catheter wherein the inner medical element has a longitudinal axis and a second curve controllably formed which has a second radius of curvature. The most proximal of the first and second curves in operation is a direction defining curve wherein the longitudinal axis of the catheter tube immediately proximal the direction defining curve defines an up-going direction and an opposite down-going direction. The up-going direction is parallel to the longitudinal axis immediately proximal the direction defining curve and is the direction in which any fluid flowing through the catheter tube immediately proximal the direction defining curve would flow if the fluid were passing from the proximal to the distal end of the catheter tube. The shape of the combination catheter is then varied to form both up-going and down-going catheter configurations during a single medical procedure, wherein the shape of the combination catheter is varied by relative manipulation of the curved catheter tube and the inner medical element. The first curve is disposed a distance from the extreme distal tip of the catheter tube not substantially greater than three times the smaller of the first and second radii of curvature, and said second curve is disposed a distance from the extreme distal tip of the inner medical element not substantially greater than three times the smaller of the first and second radii of curvature. The first and second curves can be preformed. The first and second curves can be formed by remote control.
Although the invention is described in connection with blood vessels, it is not so limited. It may be used not only in arterial and venous structures, but also in the biliary tree, urinary tract, body cavities (such as the thorax and abdomen), hollow viscus organs (such as the stomach, intestines, and urinary bladder), cysts and abscessesxe2x80x94in short, in any place where selective direction and reformation of a catheter, tube or guidewire is required.